The outcome of total elbow arthroplasty in juvenile idiopathic arthritis (juvenile rheumatoid arthritis) patients.

Background: Elbow prosthetic replacement in patients with juvenile idiopathic arthritis (JIA) can be complicated and technically challenging. Thus, we sought to evaluate the clinical benefit and the prosthetic longevity of primary semiconstrained linked total elbow arthroplasty (TEA) performed to treat these patients.

Methods: Between 1983 and 2005, 29 elbows in 24 patients (20 women and 4 men) had been replaced because of JIA.

Anatomic shoulder arthroplasty for treatment of proximal humerus malunions.

Background: Malunion of proximal humeral fractures complicated by damage to the glenohumeral cartilage and injury to the joint capsule and rotator cuff can include treatment requiring anatomic shoulder arthroplasty. This study defines results and complications of this procedure and identifies factors associated with success or failure.

Methods: From 1976 to 2007, 109 patients underwent shoulder arthroplasty for proximal humerus malunions.

Unconstrained shoulder arthroplasty for treatment of proximal humeral nonunions.

Background: Unconstrained shoulder arthroplasty is one of several methods for treatment of proximal humeral fracture nonunions. The goal of this study was to define the results and complications of this procedure.

Methods: From 1976 to 2007, sixty-seven patients underwent unconstrained shoulder arthroplasty for proximal humeral nonunion and were followed for more than two years.

Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury.

The pathogenesis of adhesions following primary tendon repair is poorly understood, but is thought to involve dysregulation of matrix metalloproteinases (Mmps). We have previously demonstrated that Mmp9 gene expression is increased during the inflammatory phase following murine flexor digitorum (FDL) tendon repair in association with increased adhesions. To further investigate the role of Mmp9, the cellular, molecular, and biomechanical features of healing were examined in WT and Mmp9(-/-) mice using the FDL tendon repair model.

Teriparatide therapy and beta-tricalcium phosphate enhance scaffold reconstruction of mouse femoral defects.

To investigate the efficacy of endocrine parathyroid hormone treatment on tissue-engineered bone regeneration, massive femoral defects in C57Bl/6 mice were reconstructed with either 100:0 or 85:15 poly-lactic acid (PLA)/beta-tricalcium phosphate (β-TCP) scaffolds (hereafter PLA or PLA/βTCP, respectively), which were fabricated with low porosity (<30%) to improve their structural rigidity. Experimental mice were treated starting at 1 week postop with daily subcutaneous injections of 40 μg/kg teriparatide until sacrifice at 9 weeks, whereas control mice underwent the same procedure but were injected with sterile saline. Bone regeneration was assessed longitudinally using planar X-ray and quantitative microcomputed tomography, and the reconstructed femurs were evaluated at 9 weeks either histologically or biomechanically to determine their torsional strength and rigidity.

Evaluation of dense polylactic acid/beta-tricalcium phosphate scaffolds for bone tissue engineering.

Advances in biomaterial fabrication have introduced numerous innovations in designing scaffolds for bone tissue engineering. Often, the focus has been on fabricating scaffolds with high and interconnected porosity that would allow for cellular seeding and tissue ingrowth. However, such scaffolds typically lack the mechanical strength to sustain in vivo ambulatory stresses in models of load bearing cortical bone reconstruction.

Remodeling of murine intrasynovial tendon adhesions following injury: MMP and neotendon gene expression.

Tendon injury frequently results in the formation of adhesions that reduce joint range of motion. To study the cellular, molecular, and biomechanical events involved in intrasynovial tendon healing and adhesion formation, we developed a murine flexor tendon healing model in which the flexor digitorum longus (FDL) tendon of C57BL/6 mice was transected and repaired using suture. This model was used to test the hypothesis that murine flexor tendons heal with differential expression of matrix metalloproteases (MMPs), resulting in the formation of scar tissue as well as the subsequent remodeling of scar and adhesions.

Erythropoietin accelerates functional recovery after peripheral nerve injury.

Background: Erythropoietin is a naturally occurring hormone with multiple effects on a number of different cell types. Recent data have suggested neuroprotective and perhaps even neurotrophic roles for erythropoietin. We hypothesized that these functional effects could be demonstrable in standard models of peripheral nerve injury.

Adhesions in a murine flexor tendon graft model: autograft versus allograft reconstruction.

Reconstruction of flexor tendons often results in adhesions that compromise joint flexion. Little is known about the factors involved in the formation of flexor tendon graft adhesions. In this study, we developed and characterized a novel mouse model of flexor digitorum longus (FDL) tendon reconstruction with live autografts or reconstituted freeze-dried allografts.

Screw orientation and plate type (variable- vs. fixed-angle) effect strength of fixation for in vitro biomechanical testing of the Synthes CSLP.

Background Context: Two common justifications for orienting cervical screws in an angled direction are to increase pullout strength and to allow use of longer screws. This concept is widely taught and has guided implant design. Fixed- versus variable-angle systems may offer strength advantages.

Screw pull-out force is dependent on screw orientation in an anterior cervical plate construct.

Two common justifications for orienting cervical screws in an angled direction is to increase pull-out strength and to allow use of longer screws. This concept is widely taught and has guided implant design. Fixed versus variable angle systems may offer strength advantages.

Biomechanical analysis of in situ single versus double screw fixation in a nonreduced slipped capital femoral epiphysis model.

Slipped capital femoral epiphyses (SCFE) were created in 24 pairs of immature bovine femurs. In 17 pairs of femurs, the slip was left nonreduced (one-third diameter of physis), and in 7 pairs, the slip was reduced. Stabilization of the slips was with either 1 or 2 threaded 6.